That picture of Big Mom punching alongside Luffy is so hilarious, why not? It would be fun. And all her siblings are cooler than Kaido and his crew combined, and honestly, I actually like their designs over the post-timeskip SHs, for the most part. It all depends on how she responds to learning of Caramel's fate. Struesen at the very least will likely catch it.
That's one thing about Big Mom, she's a complete and utterly unrestrained Wild Card. She might do just about anything but give up on Totoland, and if she learns Caramel wasn't even into that and was actually a slave trader... wow.
Considering all the WG experiments concerning Gigantification, her abnormal strength and disorders to her personality, whereby she goes berserk if she goes long enough without a specific and seemingly randomly selected food, is eerily similar to the children of Punk Hazard who went without their poisoned "Candy" for too long. It would not surprise me to learn she was an early, and successful, Gigantification experiment. Her flaw was her berserk state, possibly a side effect of whatever was used to mutate her, and they lost control at the outset.
Given she's got holes in her memory from her Hunger Pang rampages, atop this amnesia, indicates she may have had other instances of amnesia as well, atop being 70-something and at a point in life where she very well could be on the verge of going well and truly senile. I don't see a reason for the potential she couldn't have flashbacks of something new atop what we already know.
If she is a WG experiment, anything's possible. Vegapunk might want her. The WG might try to capture her. The Giants hate her, so if the resolution's in Elbaf, who knows? She could either go back to rule Totland as the semi-benevolent ruler she's always been, or she could agree to join Straw Hats and help him be Pirate King. Or maybe she dies by shock from revelations or some other factor. I highly doubt Luffy will directly fight her. She's shown to be too durable and fun to ultimately be taken out as a standard villain, unless of course she does something else to his crew. (And assuming Sanji doesn't just bribe her. Food is the ultimate bargaining tool here and Sanji has what it takes if he's clever enough).
I find it unlikely somehow that she will remain a major and consistent villain until Raftel. If she does, it'll just be more of the same. With Katakuri already liking and basically sparing and even training Luffy, one can imagine the BMP becoming allies eventually, after working out the kinks, and memory issues.
